Mercury debate gets murkier / No clear choices on which fish are best

Olivia Wu, Chronicle Staff Writer

Published 4:00 am, Wednesday, April 16, 2003

Photo: BRANT WARD

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Andronico's Market seafood specialist Jamie O'Rourke does his magic in back of a large sign warning about the mercury levels of various species of fish. This market on Irving Street in San Francisco. By Brant Ward/Chronicle less

Andronico's Market seafood specialist Jamie O'Rourke does his magic in back of a large sign warning about the mercury levels of various species of fish. This market on Irving Street in San Francisco. By Brant ... more

Photo: BRANT WARD

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Photo of Tai Snapper from New Zealand. Monterey Fish Market at Pier 33. They are a wholesale operation that gets fish from far away places such as New Zealand as well local to supply restaurants.
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Photo of Tai Snapper from New Zealand. Monterey Fish Market at Pier 33. They are a wholesale operation that gets fish from far away places such as New Zealand as well local to supply restaurants.
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Photo: CRAIG LEE

Mercury debate gets murkier / No clear choices on which fish are best

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So you jack up the amount of fish you eat, pump the omega-3s, and make your heart healthier and happier than it's ever been. But at the same time, are you accumulating toxic levels of mercury and making a mess of your brain and nerves?

It depends, scientists say.

What kind of fish, how large the fish are and your individual tolerance for mercury are all factors in choosing a mercury-safe seafood diet. You can eat fish often -- if you choose carefully.

The U.S. Food and Drug Administration lists shark, swordfish, king mackerel and tilefish as the species high in mercury, and warns children and women of childbearing age to avoid them. All four are large fish that feed on smaller fish and live long enough for high levels of mercury in the ocean to accumulate in their flesh. Some scientists think other fish that live a long time, notably tuna, belong on the list as well.

In California, where the attorney general has filed suits against several grocery and restaurant chains under Proposition 65 for not labeling mercury- contaminated fish, an interim warning sign has been created. The markets named in the first suit -- Albertsons, Safeway, Trader Joe's and Whole Foods -- are required to display the warning which, in addition to the four fish above, includes fresh and frozen tuna.

The restaurants named in a second suit filed April 10 includes Benihana, Kimpton Hotel & Restaurant Group and Ruth's Chris Steakhouse. The move is intended to force restaurants to post warnings similar to those starting to go up in grocery stores. And the California Medical Association is pressing for mercury labeling on all seafood.

So what's a dedicated fish-eater to do?

"It's really easy," says Dr. Jane Hightower, the San Francisco internist who first called attention to possible mercury poisoning from fish by studying her patients' eating habits. "We have so many other foods to choose from," she says.

The symptoms of mercury poisoning, which some of her patients had been experiencing, included depression, failed memory, hair loss and inability to focus. When the patients stopped eating fish, the symptoms cleared up. When they returned to eating fish, but chose the kinds that are not considered high in mercury, their symptoms did not return and their mercury levels remained below the danger zone.

"They eat the same number of fish meals, but a different diet. If you eat low on the predatory chain and eat fish that don't live to a mature age, your body will have a chance to clear," she says.

Wild-caught Pacific salmon in season are considered safe because they are at most 4 years old -- not old enough to have accumulated high levels of mercury. In addition, any farmed freshwater fish, small saltwater fish such as herring and anchovies, and shellfish are all considered safe.

While also considered mercury-safe, shrimp and scallops are a challenge to those who also want to eat sustainably. Most shrimp available in Northern California have been farmed in Asia, where the operation often destroys mangroves. Scallop-dredging wrecks ocean-floor habitat. But it is possible to eat spot prawns rather than farmed shrimp and to pay for diver-caught scallops.

Many kinds of ocean fish -- sole, sand dabs, rock cod -- don't present mercury hazards, but have been overfished and so are less available. The ecologically-sound choices include rock cod caught by hook-and-line or sand dabs caught by Scottish purse-seine.

Canned tuna remains one of the great unknowns when it comes to mercury. No agency is yet responsible for testing it. The FDA says it has done some testing and found mercury at safe levels. But others have tested and turned up high levels in some cans, and there are reports that Mediterranean canned tuna contains four times the mercury of domestic brands.

In addition, authorities disagree on what constitutes a safe level of mercury in canned tuna, which is widely consumed by children.

People who are worried about mercury should keep a diary of the fish they eat, says Hightower, who used this procedure in her clinic. If their intake is higher than the amounts recommended by governmental agencies, or if they have symptoms, they can ask to be tested, she says. The blood test is generally around $30.

Americans are eating about 4 billion pounds of fish a year, more than ever, in large part to vanquish heart disease. At the same time, ocean-contaminating mercury emissions from coal-fired factories and mines have increased just as dramatically across the globe. None of it is going away.

That's why, Hightower says, all seafood should now be regulated and labeled.

Mercury is ingested and accumulated by fish, and the ones that are highest in the food chain pile up the most. Too much mercury can damage the human brain and nervous system, especially in babies. In children, the damage can be permanent.

Hightower's study documented the phenomenon among a different strata of the population -- her patients. They are mostly educated, high-income Bay Area residents who eat protein-rich meaty steaks from large, predatory, ocean specimens such as shark and swordfish.

At this point it's difficult to give hard-and-fast recommendations about which fish to eat and how much.

Part of the problem is that federal authorities are at odds about how much mercury constitutes a hazard, both in fish and in people. Another part of the problem is that fish species haven't been adequately or thoroughly tested for mercury and other contaminants.

The FDA, which regulates commercial seafood, sets a much higher safe dose for both humans and fish than the EPA, which regulates fish caught through sport fishing. But the Canadian government's standards match the EPA's, not the FDA's. Hightower goes with the EPA standards.

Another issue: No one has studied or given advisories for women of non- childbearing age or for men.

small, low-on-the-chain, and not very sexy. That way you'll not only lower your mercury intake, but you'll actually increase those heart-healthy omega 3s.

Tips for selecting mercury-low seafood

-- Avoid large, long-lived predator fish.

-- Eat a variety of fish, including shellfish.

-- Eat small fish. Some experts categorize "small" as being no larger, when whole, than your plate.

-- Avoid the guts and eggs of fish.

-- If you're planning to start a family, begin following these guidelines one year before becoming pregnant.

Freshwater farmed fish, shrimp and scallops. These tend to be low in mercury, but shrimp and scallops can be raised or caught in ways that harm the environment. Choose California spot prawns and diver-harvested scallops and buy them in season.

Salmon. Wild-caught Pacific salmon is considered safer than Atlantic farmed salmon because farmed salmon are fed fish meal, which may contain mercury and dioxins. Atlantic farmed salmon aren't always sustainably raised and can be treated with antibiotics and color.

Canned tuna. The California Department of Health Services recommends eating chunk or chunk light tuna, which has less mercury than solid white or chunk white tuna.

How much fish to eat

-- Do not eat shark, swordfish, tilefish or king mackerel.

-- If there are no other specific advisories, follow these guidelines:

Each week, up to 1 pound (uncooked weight) of fresh or frozen fish bought in stores, OR two 6-ounce cans of tuna, OR up to 1 pound (uncooked weight) of fish from local ocean or saltwater bays, OR up to 1/2 pound (uncooked weight) of local freshwater fish.

Other adults: No recommendations given.

Children:

-- Do not eat shark, swordfish, tilefish or king mackerel.

-- Each week, up to 3 ounces (uncooked weight) of sport-caught freshwater fish.

To measure:

-- 3 ounces of fish is about the size of a deck of cards.

-- 8 ounces (1/2 pound) of uncooked fish is about the size of a thin paperback book

Now Playing:

-- 1 pound of uncooked fish equals about 3/4 pound of cooked fish.

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